[PATCH] D131453: LiveDebugValues: Fix another crash related to unreachable blocks

[Adrian Prantl via Phabricator via llvm-commits]

aprantl created this revision.
aprantl added reviewers: jmorse, StephenTozer.
Herald added a subscriber: hiraditya.
Herald added a project: All.
aprantl requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

This is a follow-up patch to D130999 <https://reviews.llvm.org/D130999>. In the test, the MIR contains an unreachable MBB but the code attempts to look it up in MLocs. This patch fixes this issue by checking for the default-constructed value.


https://reviews.llvm.org/D131453

Files:
  llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
  llvm/test/DebugInfo/MIR/X86/ldv_unreachable_blocks2.mir


Index: llvm/test/DebugInfo/MIR/X86/ldv_unreachable_blocks2.mir
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/MIR/X86/ldv_unreachable_blocks2.mir
@@ -0,0 +1,32 @@
+# RUN: llc -mtriple=x86_64-apple-macos %s -start-before=livedebugvalues -filetype=obj -o - | llvm-dwarfdump - | FileCheck %s
+# CHECK: DW_TAG_subprogram
+# Test that LiveDebugValues can handle MBBs that are not reachable in a RPOT.
+--- |
+  define hidden zeroext i1 @__foo_block_invoke(i8* nocapture noundef readonly %.block_descriptor, i64 noundef %type) !dbg !7 {
+  entry:
+    unreachable
+  do.body.i129.i:                                   ; preds = %if.else6.i128.i
+    unreachable
+  }
+  !llvm.dbg.cu = !{!3}
+  !llvm.module.flags = !{!5, !6}
+  !2 = !{}
+  !3 = distinct !DICompileUnit(language: DW_LANG_C99, file: !4, producer: "clang", runtimeVersion: 0, emissionKind: FullDebug)
+  !4 = !DIFile(filename: "t.c", directory: "/")
+  !5 = !{i32 2, !"Debug Info Version", i32 3}
+  !6 = !{i32 1, !"LTOPostLink", i32 1}
+  !7 = distinct !DISubprogram(name: "__foo_block_invoke", scope: !4, file: !4, line: 573, type: !9, scopeLine: 573, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !3, retainedNodes: !2)
+  !9 = !DISubroutineType(types: !2)
+  !11 = !DILocalVariable(name: ".block_descriptor", arg: 1, scope: !7, file: !4, line: 557, type: !12, flags: DIFlagArtificial)
+  !12 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 64)
+  !13 = !DICompositeType(tag: DW_TAG_structure_type, name: "__block_literal_1", scope: !4, file: !4, line: 557, size: 392, elements: !2)
+  !15 = !DILocation(line: 558, column: 7, scope: !7)
+name:            __foo_block_invoke
+body:             |
+  bb.0.entry:
+    DBG_VALUE $rdi, $noreg, !11, !DIExpression(), debug-location !15
+    $ecx = MOV32rr undef $edi, implicit $dil, debug-location !15
+  bb.2:
+    successors: 
+    TRAP
+  bb.21.do.body.i129.i (address-taken):
Index: llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
===================================================================
--- llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
+++ llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
@@ -297,6 +297,8 @@
     for (auto Location : MTracker->locations()) {
       LocIdx Idx = Location.Idx;
       ValueIDNum &VNum = MLocs[Idx.asU64()];
+      if (VNum == ValueIDNum::EmptyValue)
+        continue;
       VarLocs.push_back(VNum);
 
       // Is there a variable that wants a location for this value? If not, skip.


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D131453.451003.patch
Type: text/x-patch
Size: 2592 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20220809/913838e9/attachment.bin>